Various polymer and rubber compositions, and combinations have been proposed as an attempt to achieve desirable properties such as toughness and rigidity for use in certain applications. One prior art approach teaches modification of a polymer by grafting rubber on the polymer chain backbone. A second approach involves the use of core and shell structure as an impact modifier, wherein an elastomeric core is surrounded by a polymeric shell. A third approach involves physically blending an uncured elastomer and a thermoplastic.
With respect to the field of rotational molding, polymer processors must compromise between existing resins having either a sufficient hardness or impact strength. Typical rubber modified polymers such as impact polystyrene and ABS cannot be rotationally molded easily, or even at all. The rubber component is not stable during the relatively long molding time cycles. Further problems include inconsistent, non-uniform melt flow of the different polymer components of the blend, and molded articles exhibiting webbing and/or having rough surface textures.
Even though various elastomeric polymer combinations exist, the molding and processing industry still seeks polymeric compositions which are toughened and exhibit hardness and impact resistance, while being processable in conventional equipment.